An adhesive containing a polyurethane as the main component exhibits good adhesive property to various adherends such as plastics, woods, and metals. The adhesive is used in various applications because the adhesive exhibits a wide range of physical properties from hard to soft according to a combination of various isocyanate group-containing compounds with various active hydrogen group-containing compounds as raw materials.
On the other hand, a structural adhesive used in assembly such as automobiles, other vehicles and airplanes requires high rigidity in order to improve torsional rigidity of body in addition to adhesive property. Further, it is desired that the structural adhesive has excellent fracture toughness as index for decreasing adhesive failure during collision.
Patent Document 1 discloses a urethane resin adhesive suitable for a structural adhesive of vehicles. However, the adhesive using as the main component the polyurethane had difficulty in the compatibility of high rigidity and adhesiveness.
In addition, a coating agent in which fragility as defect of an epoxy coating material is improved and highly hard property is exhibited is desired, in coated structural bodies such as flooring materials, paving materials and the like.
Further, it is required that a urethane composite material reinforced with reinforced-fibers has high elastic modulus, and then it is important to satisfy both high elastic modulus and toughness.
However, the curable resin composition containing the polyurethane as the main component had difficulty in the compatibility of high rigidity (for example, high elastic modulus), and adhesiveness and/or toughness.